Transcript

2.
Earth’s Layers The Earths rocky outer crust solidified billions of years ago, soon after the Earth formed. This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle.

7.
Plate Tectonics• Greek – “tektonikos” of a builder• Pieces of the lithosphere that move around• Each plate has a name• Fit together like jigsaw puzzles• Float on top of mantle similar to ice cubes in a bowl of water

8.
Continental Drift Alfred Wegener 1900’s Continents were once a single land mass that drifted apart. Fossils of the same plants and animals are found on different continents Called this supercontinent Pangea, Greek for “all Earth” 245 Million years ago Split again – Laurasia & Gondwana 180 million years agohttp://members.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml

11.
Sea Floor Spreading• Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins• Magma rises to the surface and solidifies and new crust forms• Older Crust is pushed farther away from the ridge

23.
Review• Name the 3 main layers of the Earth• What is a tectonic plate?• What was Pangea?• What is Sea-Floor spreading?• Name the three different types of plate boundaries and one location on Earth for each one